

File: Description_Kemmel_Track_R03.txt
R01 - 2011 Mar 26 - hdrake - TabbyCat Robots
R02 - 2011 Apr 07 - hdrake - TabbyCat Robots
R03 - 2011 Jul 24 - hdrake - TabbyCat Robots


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Here is a description of my Spa racetrack for NXT line following robots.

A robot can follow a simple loop around the whole track.  It will have
long straghts and some twisty parts.  For this simple loop, the black line
is continuous except for two 3/8" gaps of white.  This is where other
lanes merge in.  As this is an angled / tapered gap, the momemtum of the
robot will probably carry the robot across without a wild course correction.

There will be some colored markers on the track, that will indicate passing
lanes, and pit areas, and the robot can react to these.

The lines to be followed are black and the track is white.

There are colored markers on the track that act as instructions to the
robots.

The main feature of the track is a straightaway approx. 18 ft. long.

The track is 30 in. wide, and 3 lanes wide in some areas.

Design for lanes that are 9 1/4 in. wide.
Yes, the track is 30" wide, but that is between the catch fences on either
side of the track.  It is probably better if your robot does not catch
its wheels in the fence.

In areas with 3 lanes, the black lines are laid out such that the
left side of the lines are 4 1/2 in., 13 3/4 in, and 23 in. from the left
side of the track.

The black lines are approx. 15/16 in. wide, except on the long straight
where they 2 in. wide.  This is to allow for some wobble at very
high speeds.

Lines are laid out such that the robot should follow the left side of 
the line.

The minimum radius of curves in the pit lane is 4-1/2 in.

The radius of the curve immediately after the red marker in the pit
stall is 3" for a very short distance.  The black line is wider here
and this has given no problem to the robots.

The minimum radius of curves on the racing line is 7-1/2 in.,
with the exception of 1 or 2 curves with a 4 in radius.  These
will be preceeded by a special marker.

There will be barriers (catch fences) on the sides of the tables
to prevent robots from falling onto the floor.   (Unless you have
an SUV robot that can scale a 5 in. high barrier.)

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Colored Road Markers
The colored road markers are stickers on the racetrack.

The markers are 2 in. wide.

The markers overlap the black line and are set in approx 1/2 in.
i.e., the left side of the marker is 1/2 in from the left side
of the black line and the right side of the marker is 2-1/2 in.
from the left side of the black line.  (Yes, the robot will probably
need 2 sensors, one to follow the black line, and one to read the
colored markers.)

As the robot travels the black line, it will see markers as follows.

(I will use the quote symbol ", for inch.)

Markers on the main racing line.
----------------------------------------------------
1" black, 2" green, 1" black - okay to accelerate - straight track
ahead.  At the start of the long straights, there will be 1 to 4 of
these green markers.  There will be red markers, (see next description),
at the end of the straight.  Or there may be a red marker at the start
of a sequence of curves, and a matching green markder at the end.

1" black, 2" red, 1" black - curve ahead - you'd better slow down.  The
number of red markers gives an indication of the tightness or difficulty
of the curve ahead.



1" black, 2" blue, 2" green, 1" black - additional lane to right,
okay to change lanes to right.  If preceeded by a "pit pit entrance
ahead - 1" black, 2" yellow, 2" green, 1" black", then pit entrance to
right.

1" black, 2" blue, 2" red, 1" black - additional lane to left,
okay to change lanes to left.  If preceeded by a "pit pit entrance
ahead - 1" black, 2" yellow, 2" green, 1" black", then pit entrance to
left.

1" black, 2" blue, 2" yellow, 1" black - located on a curve -additional
lane by leaving line and going straight.  If preceeded by a "pit
pit entrance ahead - 1" black, 2" yellow, 2" green, 1" black", then
enter pit lane by going straight.



1" black, 2" yellow, 2" red, 1" black - start finish line.

1" black, 2" yellow, 2" blue, 1" black - very sharp curve ahead - you'd
better slow down a lot.



Parallel to the Start-Finish straight, there will be a pit lane.  A
robot will be able to continue on the race line, and circulate
around the track.  Or it can react to the following marker and make
a pit stop.
1" black, 2" yellow, 2" green, 1" black - pit entrance ahead.  



Markers on the pit entrance line.
----------------------------------------------------
1" black, 2" green, 1" black - pit stalls are to the right, while proceeding
down pit lane.  Also indicates the end of pit entrance and the beginning of
pit lane.

1" black, 2" red, 1" black - pit stalls are to the left, while proceeding
down pit lane.  Also indicates the end of pit entrance and the beginning of
pit lane.



Markers on the pit lane line.
----------------------------------------------------
All robots will be assigned a color, green, red, yellow, blue.
This will identify its pit stall.

As a robot proceeds down pit lane, it will detect the following
markers.

1" black, 2" green, 1" black - pit stall for green car is to left or right.


1" black, 2" red, 1" black - pit stall for red car is to left or right.


1" black, 2" yellow, 1" black - pit stall for yellow car is to left or right.


1" black, 2" blue, 1" black - pit stall for blue car is to left or right.


1" black, 2" yellow, 2" green, 1" black - pit exit begins.  Okay to accelerate
when detecting 1" black, 2" green, 1" black.



Markers on the pit stall line.
----------------------------------------------------
1" black, 2" red, 1" black - the robot should stop and wait for button
press before proceeding.  (Note that the yellow robot may now have to
not react to 1" black, 2" yellow (it may be start of the 1" black, 2" yellow,
2" green, 1" black - pit exit start), as its pit stall, depending on your
programming.)
When the button is pressed, the robot will move back to the pit lane black
line, and follow back onto the racing line.  By the AFOL pushing various
buttons, the robot may ignore or act on lane change color markers on the
track, or do other tricks.



Markers on the pit exit line.
----------------------------------------------------
1" black, 2" green, 1" black - okay to accelerate - prepare to merge onto
main racing line.




Description of black line at lane changes and pit entance.
----------------------------------------------------------------------
When a robot detects a marker for lane change or pit entrance,
it should:
1.  Turn about 45 degrees left or right.
2.  Proceed about 4 inches across the colored marker and white space.
3.  Start looking for a black line, that will be about 1 inch to 8
    inches from the previous black line.
4.  When the bleck line is detected, start following it.  It will
    lead to the adjacent lane, or the pit lane.

When 2 black lines (lanes) merge, there may be a short space (~3/8")
without black line.



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Robot specs: (For open track time at BrickFair 2011)

Robots may be built around NXT, RCX, Spybot, or other intelligent bricks.

Maximum robot width:  8 inches
Maximum robot width with any or all caster wheels turned out: 8-1/2 inches.

Maximum robot length:  13 inches

All parts of the robot, except, of course, tires, must clear the track by
1/4 inch, preferably 3/8 inch.

All robots must have a driver and/or passenger - minifig, technic guy,
etc.

The robot may have 1, 2, or 3 motors.

The robot can have ultrasonic or touch sensors to prevent knocking any
leading robots off track.

Wheel / Tire size is open.

Maximum vehicle height is 8-1/2 inches.

Robots may have one or two intelligent bricks.

Robots may have all of the intelligence for controlling the robot
residing in the programs on board the robot.

Or the robot may take some instructions from remote controls, cell
phones, laptops, etc.

When the robot is stopped in its pit stall, the pit crew can reprogram the
NXT, change tires size, etc.  Anything you can do in 60 seconds.  Remember
this is an F1 race, where the typical pit crew can change 4 tires in 3
seconds.  Otherwise, move the robot to the garage area, and let another AFOL
run her robot.

When doing wobbly line following and simulating texting while driving,
minifigs on 2 robots can use the blue tooth connection - lots of
imagination required to program this.

Robots can have any number of forward and/or reverse speeds, but the
track is designed for 6 speeds.  And remember that a robot's speed is
related to motor power, gearing, and tire diameter.

Ideas for 6 speeds from slowest to fastest:

Pit lane - use in pit lane  e.g. 20% power.

Slow curve - for 4 inch radius curves  e.g. 30% power.

Standard - for short straights and sweeping curves  e.g. 40% power.

Straight Line - a little faster  e.g. 50% power.

Very Fast - Yes!  e.g. 60% power.

Max Speed - Now the fun begins!!!  e.g. 70% - 100% power.  Remember that
as the power approaches 100%, steering correction becomes trickier.



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References
----------
I firmly believe in Isaac Newton's quote:
"If I have seen further it is only by standing on the shoulders of giants."
or "Give credit where credit's due."

My NXC line following code is from ideas in the NXT-G program LineFollowPro,
at http://www.nxtprograms.com/line_follower.
I could not find an author's name.

Lego Mindstorms NXT Power Programming
Robotics In C
Second Edition
John C. Hansen

Creating Cool Mindstorms NXT Robots
Daniele Benedettelli

An Introduction to ANSI C on Unix
Paul S. Wang

NXC Programmers Guide
June 8, 2010
by John Hansen
NXC
Version 1.2.1 r3

Programming LEGO NXT Robots using NXC
(beta 30 or higher)
(Version 2.2, June 7, 2007)
by Daniele Benedettelli
with revisions by John Hansen

The Lego Mindstorms NXT 2.0 Discovery Book
Laurens Valk


 